Cytochrome c methylation in Neurospora crassa will be used as a model system to advance our knowledge about the functional relationship of protein methylation to an organism. The investigation will be designated to achieve the following primary objectives: a) The purification of the N. crassa cytochrome c-specific methyltransferase, with subsequent chemical and physical characterization, including an investigation of the structural features of the cytochrome c molecule required for its role as a methyl acceptor. b) To examine cytochrome c methylation in relation to the physiological and developmental status of the cell, with emphasis on the temporal relationship between the synthesis of the methylating enzyme and cytochrome c synthesis. c) To determine the intracellular site of cytochrome c meyhylation, i.e., whether on the polysome, cytosol or in the mitochondria. (d) To explore the functional significance to the organism of cytochrome c methylation; specifically whether it enhances its transport into the mitochondria or changes its binding capacity to cytochrome c oxidase.